Photovoltaic–thermal (PV/T) solar collectors convert solar radiation into electrical power and heat. Part of received solar energy can be lost to the atmosphere from the top surface of the PV/T module, especially in windy regions. Thus, in this study, a new vacuum-based photovoltaic thermal (VPV/T) collector is designed and comparatively analyzed with the conventional PV/T collector. The new design differs from the conventional PV/T design by including a vacuum layer above the silicon wafer. Besides, to enhance the heat dissipation from the silicon wafer in the VPV/T design to the thermal absorber, the thicknesses of ethylene-vinyl acetate and tedlar polyester tedlar layers underneath the silicon wafer are decreased. A comprehensive 3D conjugate thermal model is developed and validated. The comparison is conducted under steady and transient conditions. The effects of Reynolds number (Re), wind speed, glass emissivity, and vacuum pressure are investigated. And finally, exergy analysis results for both designs are compared. The results showed that the new VPV/T collector has accomplished a 26.6% increase in the thermal power without changing the electrical power gain at Re of 50 and solar irradiance of 1000 W m⁻². In addition, the vacuum pressure degradation from 0.01 Pa to 10 Pa slightly decreases the gained thermal power of the new VPV/T collector. A further increase in the vacuum pressure from 10 Pa to 1.013 × 10⁵ Pa significantly decreases the gained thermal power with a slight increase in the electrical power. Furthermore, the total predicted VPV/T and the conventional PV/T exergy efficiency are 39.6% and 32%, respectively.

The thermal management of high-heat-density devices is essential for reliable operation. In this work, a novel procedure is proposed and investigated for the efficient thermal management of such devices. The proposed procedure introduces different arrangements of metal inserts within a cooling channel heat sink. The objective of those inserts is to form boundary layers to prevent any hot spots from appearing within the flow and increase temperature uniformity. Five different arrangements are introduced and numerically investigated using the commercial software package ANSYS FLUENT 2021R1. The model was validated against previous findings and showed a good agreement with errors of less than 5.5%. The model was then used to study the heat transfer characteristics of the proposed cases compared to traditional straight channels under the same operating conditions. All the proposed arrangements displayed better heat transfer characteristics than the traditional configuration within the studied range. They also exhibited lower temperature nonuniformities, implying better temperature distribution. The temperature contours over the heat source top surface and the flow streamlines are also introduced. Among all the proposed arrangements cases, a microchannel with micro metal insert located at the top wall along with a second row of inserts covering two-thirds of the bottom wall is studied. This case achieved the best heat transfer characteristics and highest temperature uniformity, making it a viable candidate for high power density devices’ thermal management.